---
title: "Sizing an electric truck charging depot | Entogo"
description: "A 30-tractor depot running 180 mi a day at 2.0 kWh/mi moves 10,800 kWh to the batteries, needs 1,451.6 kW of average AC power across an 8-hour window and…"
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datePublished: 2026-10-01
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Home › Insights › How much power does an electric truck depot need? Sizing from kWh per day and dwell time

EV Charging

# How much power does an electric truck depot need? Sizing from kWh per day and dwell time

Entogo October 1, 2026

![DC fast charging station for electric trucks beside transmission grid infrastructure](https://entogo.ca/_astro/electric-truck-depot-charging-power-sizing.ChJcvEz2_1F3zyJ.webp)

Photo — Eldo Rafael · [Unsplash](https://unsplash.com/photos/a-group-of-gas-pumps-sitting-next-to-each-other-iLrMw5v4afE) · [Unsplash License](https://unsplash.com/license)

In short

A 30-tractor depot running 180 mi a day at 2.0 kWh/mi moves 10,800 kWh to the batteries, needs 1,451.6 kW of average AC power across an 8-hour window and a 2,000 kVA transformer. Energy sets the floor; NEC 625.42 and CEC 8-106(10) set the code load.

## Key takeaways

- A depot is sized from energy, not nameplates — 30 tractors at 180 mi and 2.0 kWh/mi move 10,800 kWh to the batteries and need 1,451.6 kW of average AC power across an 8-hour window.
- NEC 625.42 makes EVSE a continuous load and 625.41 sets the overcurrent device at 125 % of its rating, so ten 160 kW dispensers read as 1,737.8 kVA and a 2,500 kVA transformer.
- With load management the code load becomes the controller ceiling — NEC 625.42(A) through 750.30(C)(1)(1), or CEC Rule 8-106(10) in Canada.
- A 2,000 kVA transformer at 80 % loading yields 1,584 kW, only 1.091 times the 1,451.6 kW energy floor — about 9 % schedule margin.
- Stretching the window from 8 h to 16 h takes the same depot from 2,000 kVA to 1,000 kVA, usually the lowest-cost change available.
- Holding the service at 1,000 kW needs a 4,225.5 kWh buffer at 0.90 depth of discharge, recharging in 5.00 h at 800 kW.

Fleet depots get sized the wrong way round. Someone counts the stalls, multiplies by a dispenser rating, and lands on a service either unbuildable or three times larger than the trucks will draw. A depot is an energy problem first: the trucks need a fixed number of kilowatt-hours back before dispatch, and the question is what power moves that energy inside the window the schedule allows. Thirty Class 8 tractors running 180 miles a day at 2.0 kWh/mi need 10,800 kWh at the batteries, 11,612.9 kWh at the meter, and 1,451.6 kW averaged across an 8-hour window — a 2,000 kVA transformer. The sum of their dispenser nameplates says 2,500 kVA, and NEC 625.42 makes that larger number the code load unless a controller caps it. These are the rules behind the [EV charging service capacity calculator](https://entogo.ca/tools/ev-charging-service-capacity-calculator/).

## Why is a depot sized from energy and not from charger nameplates?

A plaza is a power problem: arrivals are random, so every dispenser must meet its rating on demand. At a depot, vehicles, mileage and parked hours are known. Energy binds, power follows.

Daily energy comes from the duty cycle. The National Center for Sustainable Transportation’s review of battery-electric truck studies puts near-term long-haul consumption between **1.3 and 3.8 kWh/mi**, narrowing to 1.3–2.5 long term, with NREL’s scenarios at 2.46 and 2.51 kWh/mi for 2018 tractors. A design value of **2.0 kWh/mi** sits inside that band.

Two companion articles share the relation P = N × E ÷ (η × t). [Sizing a site without a service upgrade](https://entogo.ca/insights/ev-charging-load-management-service-upgrade/) takes E as a given (18 kWh in a 200-space Level 2 garage); here E is derived from miles and kWh/mi, which is what changes when the vehicles are tractors. [What a DC fast charging site needs](https://entogo.ca/insights/dc-fast-charging-site-transformer-switchgear-sizing/) converts [DC fast charging](https://entogo.ca/glossary/#dc-fast-charging) output kW to AC input kVA for a plaza, where no dwell-time argument applies.

## What do NEC 625 and CEC Section 86 require?

| Question | NEC 2023 | CEC (CE Code Part I) |
| --- | --- | --- |
| Is EVSE a continuous load? | **625.42** — yes | **86-302** — the connected load is continuous for Rule 8-104 |
| Device and conductor multiplier | **625.41** — OCPD at **125 %** of EVSE rating; also 210.20(A), 215.3 | **8-104(6)** — **80 %** of rating, or **100 %** under 8-104(5) if marked |
| Minimum EVSE load in a service calculation | **220.57** — the greater of **7,200 VA** or nameplate | nameplate; no equivalent floor |
| Demand factor on EVSE | none applied here; **220.57** sets the load at the greater of 7,200 VA or nameplate | **Table 38** permits demand factors above four EVSE loads, though the ESA subcommittee has recommended deleting it |
| Managed charging | **625.42(A)** — controlled load excluded from feeder and service sizing per **750.30(C)(1)(1)** | **8-106(10)** — demand load equals the EVEMS maximum; **8-106(11)** may exclude it for the Rules 8-200 to 8-210 calculations |
| Several dispensers per circuit | **625.40** exception, with an EMS per 625.42(A) or (B) | **86-300** — a separate branch circuit, or a shared one with an EVEMS under 8-106(10) or (11) |
| Controller requirements | **750.30** — must not overload any branch circuit, feeder or service | **8-500(2)** — must not exceed 8-104(5) or (6) |
| Transformer and buffer | **450.3(B)**; storage under **Article 706**, interconnect **705.12** | **26-254**; **Section 64** |

NEC **625.42** makes every dispenser continuous, so the unmanaged load is the sum of nameplates with no diversity. **625.42(A)** is the only escape.

## Worked example — 30 Class 8 tractors on an 8-hour overnight window

A regional-haul depot outside Toronto. Thirty tractors, 180 mi/day, 2.0 kWh/mi, on the yard at 20:00, dispatched at 04:00. Utility primary 13.8 kV, secondary 480Y/277 V, 160 kW DC dispensers rated at DC output. Assume an AC-input-to-DC-output efficiency of **0.93** session-average (the [Rocket DC ultra-fast charger](https://entogo.ca/products/rocket-dc-ultra-fast-charger/) is rated to 95.5 % at its peak, so 0.93 is a deliberate derate) and power factor **0.99**, both to be confirmed on the datasheet along with the dispenser’s AC input voltage. The DC plaza article uses η = 0.95, which gives a 1,421.1 kW floor and 1,701.2 kVA for ten dispensers — a 2.1 % spread landing on the same ratings.

1. **Energy delivered to the trucks.** 30 × 180 × 2.0 = **10,800 kWh** of DC energy per night.
2. **Energy at the meter.** 10,800 ÷ 0.93 = **11,612.9 kWh**. The 812.9 kWh of losses are not optional.
3. **Average AC power across the window.** 11,612.9 ÷ 8 h = **1,451.6 kW** — the energy floor; no controller or tariff goes below it while the trucks run 180 mi.
4. **Apparent power at 80 % loading.** 1,451.6 ÷ (0.99 × 0.80) = **1,832.8 kVA**.
5. **Round up the ANSI/IEEE ladder.** The next standard three-phase rating is **2,000 kVA**.
6. **Dispenser count.** Each tractor needs 360 kWh, or 360 ÷ 160 = **2.25 h**. Eight hours fits floor(8 ÷ 2.25) = **3** whole sessions per dispenser, so 30 ÷ 3 = **10 dispensers**.
7. **The unmanaged code load.** Ten 160 kW dispensers are 1,600 kW DC, or 1,600 ÷ 0.93 ÷ 0.99 = **1,737.8 kVA** at the AC input. Under 625.42 that whole figure is continuous: 1,737.8 ÷ 0.80 = 2,172.3 kVA → a **2,500 kVA** transformer, one step above the energy floor.

> P = N × d × c ÷ (η × t)

**Step 3 — average AC power across the charging window** — `P = N * d * c / (eta * t)` with N = 30 trucks, d = 180 mi, c = 2 kWh/mi, eta = 0.93 ratio, t = 8 h → **P = 1,451.6 kW**

> S = P ÷ (PF × L)

**Step 4 — transformer kVA floor at 80 % loading** — `S = P / (PF * L)` with P = 1451.6 kW, PF = 0.99 ratio, L = 0.8 ratio → **S = 1,832.8 kVA**

> h = d × c ÷ Pc

> I = S × 1000 ÷ (√3 × V)

At 480 V that is 1,737,800 ÷ (√3 × 480) = **2,090.2 A**. NEC 625.41 and 210.20(A) put the main at 1.25 × 2,090.2 = 2,612.8 A, forcing a **3,000 A** rating off the NEC 240.6(A) ladder. Add two spare bays and the unmanaged load becomes 2,085.4 kVA, 2,606.7 kVA after the derate and a **3,000 kVA** transformer — and 2,508.3 A, which after the 125 % multiplier is 3,135.4 A and a **4,000 A** main. Spare bays are cheap; the pad, main and feeder they drag along are not.

A 2,000 kVA unit at 80 % loading and 0.99 power factor delivers 2,000 × 0.80 × 0.99 = **1,584 kW**. Against the 1,451.6 kW floor that is **1.091**, about 9 % headroom — a cold night or one late truck, not a route extension. Setting the [EVEMS](https://entogo.ca/glossary/#evems-load-management) ceiling at 1,584 kW is what makes the 2,000 kVA choice legal under 625.42(A), and what makes it tight.

| Design | Code load | Transformer | Main at 480 V |
| --- | --- | --- | --- |
| Energy floor only (no code basis alone) | 1,451.6 kW | 2,000 kVA | — |
| 10 dispensers, unmanaged, NEC 625.42 | 1,737.8 kVA | **2,500 kVA** | 3,000 A |
| 12 dispensers, unmanaged, NEC 625.42 | 2,085.4 kVA | **3,000 kVA** | 4,000 A |
| 12 dispensers, EVEMS capped at 1,584 kW | 1,600.0 kVA | **2,000 kVA** | 2,500 A |
| Same, plus a 1,000 kW service limit and buffer | 1,000 kW utility | **1,500 kVA** | 1,600 A |

## What does the dwell window do to the transformer?

The window is the most leveraged variable here: energy is fixed, so power scales inversely with hours.

| Charging window | Average AC power | kVA at 0.99 PF | At 80 % loading | Transformer |
| --- | --- | --- | --- | --- |
| 6 h | 1,935.5 kW | 1,955.0 kVA | 2,443.8 kVA | 2,500 kVA |
| **8 h** | **1,451.6 kW** | **1,466.3 kVA** | **1,832.8 kVA** | **2,000 kVA** |
| 10 h | 1,161.3 kW | 1,173.0 kVA | 1,466.3 kVA | 1,500 kVA |
| 16 h | 725.8 kW | 733.1 kVA | 916.4 kVA | 1,000 kVA |

Moving dispatch from 04:00 to 06:00 takes this depot from 2,000 kVA to 1,500 kVA. NREL’s workshop report notes utilities commonly — though not consistently across all service territories — place a peak limit of **2.5 MW** on an interconnection point, owing to a common maximum size of pad-mounted transformers for secondary service. The window is often the difference between a standard service and a utility study; the same report offers **50–500 kW** as the span depot charging could cover.

## Depot reference table

At 2.0 kWh/mi, η = 0.93, PF = 0.99, an 8-hour window and 80 % loading the divisor is 0.93 × 8 × 0.99 × 0.80 = 5.89248, so [kVA](https://entogo.ca/glossary/#kva-rating) = trucks × miles × 2.0 ÷ 5.89248.

| Tractors | Daily miles | Battery energy | kVA at 80 % | Transformer |
| --- | --- | --- | --- | --- |
| 20 | 180 | 7,200 kWh | 1,221.9 kVA | 1,500 kVA |
| **30** | **180** | **10,800 kWh** | **1,832.8 kVA** | **2,000 kVA** |
| 30 | 250 | 15,000 kWh | 2,545.6 kVA | 3,000 kVA |
| 40 | 180 | 14,400 kWh | 2,443.8 kVA | 2,500 kVA |
| 50 | 180 | 18,000 kWh | 3,054.7 kVA | two 2,000 kVA |

Every row to 3,000 kVA is one [pad-mounted unit](https://entogo.ca/products/three-phase-pad-mounted-transformer/); the last is a two-transformer lineup. Note that 3,000 kVA is a common manufacturer rating, not a step on the preferred series, where 2,545.6 kVA rounds to 3,750 kVA — see [how to size a transformer](https://entogo.ca/insights/how-to-size-a-transformer-kva-selection/).

## What does the same depot look like in Canada at 600 V?

**Voltage and continuous load.** At 600 V, 1,737,800 ÷ (√3 × 600) = **1,672.2 A** instead of 2,090.2 A, and **CEC 8-104(6)**‘s ÷ 0.80 gives 2,090.2 A and a **2,500 A** main against 3,000 A at 480 V — see [choosing a facility distribution voltage](https://entogo.ca/insights/choosing-a-facility-distribution-voltage/). **8-104(5)** allows 100 % where the device is marked; the NEC gets there via the 100 %-rated-assembly exceptions to **210.20(A)** and **215.3**.

**Load management is the real divergence.** NEC 625.42(A) removes the controlled load from feeder and service sizing. **CEC 8-106(10)** instead sets the demand load equal to the EVEMS maximum, and **8-106(11)** removes it from the calculated load altogether where the EVEMS both monitors the service, feeders and branch circuits and controls the EVSE loads per **Rule 8-500** — but only for the calculations enumerated in Rules **8-200** through **8-210**, and IAEI advises relying on it only with the local authority’s consent until an EVEMS standard is published. Declare the ceiling as AC input: 1,584 ÷ 0.99 = 1,600.0 kVA, or 1,600,000 ÷ (√3 × 600) = 1,539.6 A, and 1,924.5 A after the 80 % rule — a **2,000 A** main. Declared as DC output it would also have to be divided by η. **NEC 220.57**’s 7,200 VA floor has no CEC counterpart, so [Level 2](https://entogo.ca/glossary/#level-2-ac-charging) bays in Canada are calculated at nameplate.

## Can a battery buffer hold the service down?

When the utility offers 1,000 kW and the depot needs 1,451.6 kW, storage covers the gap — the peak-shaving duty of [cutting demand charges with battery storage](https://entogo.ca/insights/cut-demand-charges-with-battery-storage/), sized by the kW-versus-kWh method in [how to size a battery energy storage system](https://entogo.ca/insights/how-to-size-a-battery-energy-storage-system-power-vs-energy/). Cap the site flat at 1,451.6 kW, take 1,000 kW from the utility, and the buffer supplies 451.6 kW to the bus for 8 hours.

> E = (P − Pu) × t ÷ (DoD × eff)

**Buffer usable energy to hold a 1,000 kW service** — `E = (P - Pu) * t / (DoD * eff)` with P = 1451.6 kW, Pu = 1000 kW, t = 8 h, DoD = 0.9 ratio, eff = 0.95 ratio → **E = 4,225.5 kWh**

> tr = E × DoD ÷ (eff × Pb)

**Buffer recharge time during the 16-hour idle period** — `tr = E * DoD / (eff * Pb)` with E = 4225.5 kWh, DoD = 0.9 ratio, eff = 0.95 ratio, Pb = 800 kW → **tr = 5 h**

The shortfall is 451.6 × 8 = 3,612.8 kWh at the bus. At a **one-way** conversion efficiency of 0.95 the cells give up 3,612.8 ÷ 0.95 = 3,803.0 kWh, and at 0.90 depth of discharge that is **4,225.5 kWh installed** with about **500 kW** of conversion. Replacing those 3,803.0 kWh costs 3,803.0 ÷ 0.95 = 4,003.1 kWh at the meter — **5.00 hours** at 800 kW spare, inside the 16-hour idle period. The 0.95 is paid both ways, so [round-trip efficiency](https://entogo.ca/glossary/#round-trip-efficiency) is about 0.90, and it is measured, not assumed.

A buffer deferring a service upgrade at a 30-truck depot is therefore a multi-megawatt-hour asset, not a 500 kWh cabinet. The storage is specified against **UL 9540** and sited to **NFPA 855** — see [battery storage fire safety](https://entogo.ca/insights/battery-storage-fire-safety-nfpa-855-ul-9540a/) — and its step-up follows [battery storage interconnection sizing](https://entogo.ca/insights/battery-storage-interconnection-transformer-sizing/). A [DC-coupled storage and charging system](https://entogo.ca/products/dc-coupled-energy-storage-charging-system/) keeps buffer and dispensers on one DC bus.

## What to specify

- **Daily energy per vehicle, in kWh, and the charging window in hours.** Energy from a telematics export or route study, not a brochure range; the window from the dispatch schedule as a guaranteed worst case. Eight hours versus ten is 500 kVA here.
- **Charger efficiency, power factor and AC input voltage.** From the datasheet at session-average conditions, not the efficiency peak. Assuming 0.95 instead of 0.93 shifts this example by 31 kW.
- **The EVEMS ceiling in kW, as AC input, and its fallback state.** NEC **750.30** bars the controller from overloading any branch circuit, feeder or service and **CEC 8-500(2)** from exceeding Rule 8-104(5) or (6); that ceiling becomes the code load under 625.42(A) or 8-106(10).
- **Transformer kVA, secondary voltage and %Z.** From the [transformer sizing calculator](https://entogo.ca/tools/transformer-sizing-calculator/) and the nameplate — %Z sets the fault current the switchgear clears.
- **Main, feeder and interrupting ratings.** NEC **240.6(A)** after the 125 % of **625.41**, or CEC **8-104(6)**, with the transformer side to **450.3(B)** or **26-254** ([overcurrent protection](https://entogo.ca/insights/transformer-overcurrent-protection-fault-current/)) and SCCR to **110.9** from the utility [available fault current](https://entogo.ca/insights/available-fault-current-sccr-what-to-specify/) letter.
- **Buffer kW, kWh and depth of discharge.** Installed and usable energy quoted separately, under **NEC Article 706**.

## Common mistakes

- **Sizing from the nameplate sum and stopping there.** Ten 160 kW dispensers read as 1,737.8 kVA and a 2,500 kVA transformer, but the fleet moves only 11,612.9 kWh in 8 hours — 1,451.6 kW average, a 2,000 kVA unit. That sum is the correct *code* load under NEC **625.42**, so the fix is a controller, not a bigger pad.
- **Dividing daily energy by 24 hours.** 11,612.9 ÷ 24 = 483.9 kW under-sizes by a factor of 3.0 against the 1,451.6 kW the 8-hour window demands. NEC **220.87** allows measured maximum demand on an existing service, never a future load averaged over a day.
- **Buying a 500 kWh buffer for a megawatt-hour problem.** Holding a 1,451.6 kW depot at a 1,000 kW service needs **4,225.5 kWh** at 0.90 depth of discharge — 8.5 times a 500 kWh cabinet.
- **Assuming diversity on charger load.** NEC **220.57** fixes the EVSE load at the greater of 7,200 VA or nameplate, so the escape is a controller under **625.42(A)**, not a 0.80 spreadsheet factor. Canada is not symmetrical: CE Code **Table 38** does allow demand factors above four EVSE loads, though the ESA subcommittee has recommended deleting it — confirm with the authority first.

## Where Entogo fits

Entogo manufactures the depot’s power train in its own roughly 20,000 m² vertically integrated factory — [three-phase pad-mounted transformers](https://entogo.ca/products/three-phase-pad-mounted-transformer/) from 75 to 2500 kVA and up to 3000 kVA at 15/25/35 kV class, [low-voltage switchboards](https://entogo.ca/products/low-voltage-switchboard/) for the 1,600–4,000 A mains these calculations land on, and [DC ultra-fast chargers](https://entogo.ca/products/category/ev-charging/) at 160/240/300 kW. Equipment is designed and built to ANSI/IEEE C57 and C37, NEC Article 625 and CEC Section 86 as the installation requires; UL (cULus)/CSA certification is available on request. Every product carries a 36-month minimum warranty, with the exact term set per product and confirmed in the contract.

Because transformers, switchgear and chargers are built in the same vertically integrated factory, a depot package can be released against one coordinated submittal rather than chased across three suppliers — which matters when the utility interconnection, not the equipment, should be the critical path. Start from the [EV charging service capacity calculator](https://entogo.ca/tools/ev-charging-service-capacity-calculator/) or the [transformer configurator](https://entogo.ca/products/transformer-quote/); see also [EV charging infrastructure](https://entogo.ca/solutions/ev-charging-infrastructure/).

Depot sizing comes down to four numbers in order: energy delivered to the trucks, energy at the meter, the window it must move through, and the ceiling a controller will enforce. The transformer, main and buffer then follow arithmetically — 10,800 kWh, 11,612.9 kWh, 8 hours, 1,584 kW, and a 2,000 kVA pad instead of a 3,000 kVA one. Take the first number from a brochure instead of the trucks and everything after it is wrong the same way.

Run the numbers

The rules in this article are the ones the calculator applies live. Enter your own load, voltages and code edition, then take the result into a specification.

[Open the calculator](https://entogo.ca/tools/ev-charging-service-capacity-calculator/)

## Sources

1. [NREL, R and D Insights for Extreme Fast Charging of Medium- and Heavy-Duty Vehicles (NREL/TP-5400-75705)](https://afdc.energy.gov/files/u/publication/extreme_fast_charging.pdf)
2. [National Center for Sustainable Transportation, The Current and Future Performance and Costs of Battery Electric Trucks (2022)](https://rosap.ntl.bts.gov/view/dot/62539/dot_62539_DS1.pdf)
3. [Electrical Safety Authority, OESC 29th Edition proposal 2024-OA-006 (CE Code Rules 8-106 and 8-500)](https://esasafe.com/assets/files/esasafe/pdf/amendments/2024/2024-OA-006.pdf)
4. [IAEI Magazine, Electric Vehicle Energy Management System (EVEMS)](https://iaeimagazine.org/columns/canadian/electric-vehicle-energy-management-system-evems-clarifying-mystery-on-this-subject/)
5. [Mike Holt Enterprises, Understanding 2023 NEC Requirements, Article 625 Electric Vehicle Power Transfer System](https://www.mikeholt.com/files/PDF/23_SOLAR_Article_625.pdf)
6. [ExpertCE, How to Calculate EVSE Load Requirements per NEC 2023](https://expertce.com/courses/electricians-guide-for-nec-2023/lessons/how-to-calculate-evse-load-requirements-per-nec-2023/)
7. [Bill Burr, Guide to the Canadian Electrical Code Part I, Section 86 (Rules 86-300 and 86-302)](https://electricalindustry.ca/latest-articles/bill-burr-section-86/)
8. [EC and M, Energy Management Systems and the NEC (Article 750)](https://www.ecmweb.com/national-electrical-code/article/20899061/energy-management-systems-and-the-nec)

- EV Charging
- Site Power
- NEC 625
- EVEMS
- Transformers
- Energy Storage

Glossary: [Level 2](https://entogo.ca/glossary/#level-2-ac-charging) [DC fast charging](https://entogo.ca/glossary/#dc-fast-charging) [Demand factor](https://entogo.ca/glossary/#demand-factor) [Battery energy storage system](https://entogo.ca/glossary/#bess) [Round-trip efficiency](https://entogo.ca/glossary/#round-trip-efficiency) [UL 9540 and UL 9540A](https://entogo.ca/glossary/#ul-9540-9540a)

FAQ

## Common questions

- **How much power does a 30-truck electric depot need?**: At 180 miles a day and 2.0 kWh per mile, 30 tractors need 10,800 kWh at the batteries. At 93 % charger efficiency that is 11,612.9 kWh of AC energy, or 1,451.6 kW averaged over an 8-hour window, which lands on a 2,000 kVA transformer at 80 % loading.
- **How many 160 kW chargers does a 30-truck depot need?**: Each tractor takes 360 kWh, or 2.25 hours at 160 kW. An 8-hour window fits three whole sessions per dispenser, so 30 trucks need 10 dispensers. Adding two spare bays does not change the energy floor but it does raise the unmanaged code load.
- **Can a depot be sized below the sum of its charger nameplates?**: Yes, with load management. NEC 625.42(A) leaves the controlled EVSE load out of feeder and service sizing under 750.30(C)(1)(1). Without a controller, 625.42 treats every dispenser as a continuous load and 625.41 requires 125 % overcurrent protection.
- **What does the Canadian Electrical Code say about EVEMS at a depot?**: CEC Rule 8-106(10) sets the demand load equal to the maximum load the EVEMS allows. Rule 8-106(11) can leave it out of the calculated load entirely for the Rules 8-200 to 8-210 calculations, subject to the local authority. Rule 86-302 still classes the connected load as continuous.
- **How big a battery buffer holds a depot service at 1,000 kW?**: Against a 1,451.6 kW flat draw over 8 hours the shortfall is 3,612.8 kWh. At 0.90 depth of discharge and 95 % efficiency the buffer needs 4,225.5 kWh of installed energy and about 500 kW of power, not a single 500 kWh cabinet.
- **Why does 600 V beat 480 V at a truck depot?**: The same 1,737.8 kVA draws 2,090.2 A at 480 V but only 1,672.2 A at 600 V. After the continuous-load rule that is a 3,000 A main versus a 2,500 A main, one frame size and one bus rating lower.
- **How many amps is a 2,000 kVA transformer at 480 V?**: Two million divided by the square root of 3 times 480 gives 2,405.6 A of full-load secondary current. At 80 % continuous loading the usable figure is about 1,924.5 A.

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## Related insights

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{"@context":"https://schema.org","@type":"Article","headline":"How much power does an electric truck depot need? Sizing from kWh per day and dwell time","description":"A 30-tractor depot running 180 mi a day at 2.0 kWh/mi moves 10,800 kWh to the batteries, needs 1,451.6 kW of average AC power across an 8-hour window and a 2,000 kVA transformer. Energy sets the floor; NEC 625.42 and CEC 8-106(10) set the code load.","image":"https://entogo.ca/_astro/electric-truck-depot-charging-power-sizing.ChJcvEz2.jpg","author":{"@id":"https://entogo.ca/#organization"},"publisher":{"@id":"https://entogo.ca/#organization"},"mainEntityOfPage":"https://entogo.ca/insights/electric-truck-depot-charging-power-sizing/","inLanguage":"en","datePublished":"2026-10-01T00:00:00.000Z","dateModified":"2026-10-01T00:00:00.000Z","keywords":"EV Charging, Site Power, NEC 625, EVEMS, Transformers, Energy Storage","abstract":"A depot is sized from energy, not nameplates — 30 tractors at 180 mi and 2.0 kWh/mi move 10,800 kWh to the batteries and need 1,451.6 kW of average AC power across an 8-hour window. NEC 625.42 makes EVSE a continuous load and 625.41 sets the overcurrent device at 125 % of its rating, so ten 160 kW dispensers read as 1,737.8 kVA and a 2,500 kVA transformer. With load management the code load becomes the controller ceiling — NEC 625.42(A) through 750.30(C)(1)(1), or CEC Rule 8-106(10) in Canada. A 2,000 kVA transformer at 80 % loading yields 1,584 kW, only 1.091 times the 1,451.6 kW energy floor — about 9 % schedule margin. Stretching the window from 8 h to 16 h takes the same depot from 2,000 kVA to 1,000 kVA, usually the lowest-cost change available. Holding the service at 1,000 kW needs a 4,225.5 kWh buffer at 0.90 depth of discharge, recharging in 5.00 h at 800 kW.","citation":[{"@type":"CreativeWork","name":"NREL, R and D Insights for Extreme Fast Charging of Medium- and Heavy-Duty Vehicles (NREL/TP-5400-75705)","url":"https://afdc.energy.gov/files/u/publication/extreme_fast_charging.pdf"},{"@type":"CreativeWork","name":"National Center for Sustainable Transportation, The Current and Future Performance and Costs of Battery Electric Trucks (2022)","url":"https://rosap.ntl.bts.gov/view/dot/62539/dot_62539_DS1.pdf"},{"@type":"CreativeWork","name":"Electrical Safety Authority, OESC 29th Edition proposal 2024-OA-006 (CE Code Rules 8-106 and 8-500)","url":"https://esasafe.com/assets/files/esasafe/pdf/amendments/2024/2024-OA-006.pdf"},{"@type":"CreativeWork","name":"IAEI Magazine, Electric Vehicle Energy Management System (EVEMS)","url":"https://iaeimagazine.org/columns/canadian/electric-vehicle-energy-management-system-evems-clarifying-mystery-on-this-subject/"},{"@type":"CreativeWork","name":"Mike Holt Enterprises, Understanding 2023 NEC Requirements, Article 625 Electric Vehicle Power Transfer System","url":"https://www.mikeholt.com/files/PDF/23_SOLAR_Article_625.pdf"},{"@type":"CreativeWork","name":"ExpertCE, How to Calculate EVSE Load Requirements per NEC 2023","url":"https://expertce.com/courses/electricians-guide-for-nec-2023/lessons/how-to-calculate-evse-load-requirements-per-nec-2023/"},{"@type":"CreativeWork","name":"Bill Burr, Guide to the Canadian Electrical Code Part I, Section 86 (Rules 86-300 and 86-302)","url":"https://electricalindustry.ca/latest-articles/bill-burr-section-86/"},{"@type":"CreativeWork","name":"EC and M, Energy Management Systems and the NEC (Article 750)","url":"https://www.ecmweb.com/national-electrical-code/article/20899061/energy-management-systems-and-the-nec"}],"about":[{"@id":"https://entogo.ca/glossary/#level-2-ac-charging"},{"@id":"https://entogo.ca/glossary/#dc-fast-charging"},{"@id":"https://entogo.ca/glossary/#demand-factor"},{"@id":"https://entogo.ca/glossary/#bess"},{"@id":"https://entogo.ca/glossary/#round-trip-efficiency"},{"@id":"https://entogo.ca/glossary/#ul-9540-9540a"}]}
```

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```

```json
{"@context":"https://schema.org","@type":"FAQPage","mainEntity":[{"@type":"Question","name":"How much power does a 30-truck electric depot need?","acceptedAnswer":{"@type":"Answer","text":"At 180 miles a day and 2.0 kWh per mile, 30 tractors need 10,800 kWh at the batteries. At 93 % charger efficiency that is 11,612.9 kWh of AC energy, or 1,451.6 kW averaged over an 8-hour window, which lands on a 2,000 kVA transformer at 80 % loading."}},{"@type":"Question","name":"How many 160 kW chargers does a 30-truck depot need?","acceptedAnswer":{"@type":"Answer","text":"Each tractor takes 360 kWh, or 2.25 hours at 160 kW. An 8-hour window fits three whole sessions per dispenser, so 30 trucks need 10 dispensers. Adding two spare bays does not change the energy floor but it does raise the unmanaged code load."}},{"@type":"Question","name":"Can a depot be sized below the sum of its charger nameplates?","acceptedAnswer":{"@type":"Answer","text":"Yes, with load management. NEC 625.42(A) leaves the controlled EVSE load out of feeder and service sizing under 750.30(C)(1)(1). Without a controller, 625.42 treats every dispenser as a continuous load and 625.41 requires 125 % overcurrent protection."}},{"@type":"Question","name":"What does the Canadian Electrical Code say about EVEMS at a depot?","acceptedAnswer":{"@type":"Answer","text":"CEC Rule 8-106(10) sets the demand load equal to the maximum load the EVEMS allows. Rule 8-106(11) can leave it out of the calculated load entirely for the Rules 8-200 to 8-210 calculations, subject to the local authority. Rule 86-302 still classes the connected load as continuous."}},{"@type":"Question","name":"How big a battery buffer holds a depot service at 1,000 kW?","acceptedAnswer":{"@type":"Answer","text":"Against a 1,451.6 kW flat draw over 8 hours the shortfall is 3,612.8 kWh. At 0.90 depth of discharge and 95 % efficiency the buffer needs 4,225.5 kWh of installed energy and about 500 kW of power, not a single 500 kWh cabinet."}},{"@type":"Question","name":"Why does 600 V beat 480 V at a truck depot?","acceptedAnswer":{"@type":"Answer","text":"The same 1,737.8 kVA draws 2,090.2 A at 480 V but only 1,672.2 A at 600 V. After the continuous-load rule that is a 3,000 A main versus a 2,500 A main, one frame size and one bus rating lower."}},{"@type":"Question","name":"How many amps is a 2,000 kVA transformer at 480 V?","acceptedAnswer":{"@type":"Answer","text":"Two million divided by the square root of 3 times 480 gives 2,405.6 A of full-load secondary current. At 80 % continuous loading the usable figure is about 1,924.5 A."}}],"inLanguage":"en"}
```

```json
{"@context":"https://schema.org","@type":"HowTo","name":"How much power does an electric truck depot need? Sizing from kWh per day and dwell time — Worked example — 30 Class 8 tractors on an 8-hour overnight window","step":[{"@type":"HowToStep","position":1,"name":"Energy delivered to the trucks.","text":"Energy delivered to the trucks. 30 × 180 × 2.0 = 10,800 kWh of DC energy per night."},{"@type":"HowToStep","position":2,"name":"Energy at the meter.","text":"Energy at the meter. 10,800 ÷ 0.93 = 11,612.9 kWh. The 812.9 kWh of losses are not optional."},{"@type":"HowToStep","position":3,"name":"Average AC power across the window.","text":"Average AC power across the window. 11,612.9 ÷ 8 h = 1,451.6 kW — the energy floor; no controller or tariff goes below it while the trucks run 180 mi."},{"@type":"HowToStep","position":4,"name":"Apparent power at 80 % loading.","text":"Apparent power at 80 % loading. 1,451.6 ÷ (0.99 × 0.80) = 1,832.8 kVA."},{"@type":"HowToStep","position":5,"name":"Round up the ANSI/IEEE ladder.","text":"Round up the ANSI/IEEE ladder. The next standard three-phase rating is 2,000 kVA."},{"@type":"HowToStep","position":6,"name":"Dispenser count.","text":"Dispenser count. Each tractor needs 360 kWh, or 360 ÷ 160 = 2.25 h. Eight hours fits floor(8 ÷ 2.25) = 3 whole sessions per dispenser, so 30 ÷ 3 = 10 dispensers."},{"@type":"HowToStep","position":7,"name":"The unmanaged code load.","text":"The unmanaged code load. Ten 160 kW dispensers are 1,600 kW DC, or 1,600 ÷ 0.93 ÷ 0.99 = 1,737.8 kVA at the AC input. Under 625.42 that whole figure is continuous: 1,737.8 ÷ 0.80 = 2,172.3 kVA → a 2,500 kVA transformer, one step above the energy floor."}],"inLanguage":"en"}
```

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